Problem: If $a + b + c = -5$ and $x + y + z = 10$, what is $5a + 6z + 5b + 5c + 6y + 6x$ ?
Explanation: $= 5a + 5b + 5c + 6x + 6y + 6z$ $= (5) \cdot (a + b + c) + (6) \cdot (x + y + z)$ $= (5) \cdot (-5) + (6) \cdot (10)$ $= -25 + 60$ $= 35$